The present invention relates to an output balance diagnostic apparatus used for an internal combustion engine and in particular to such an apparatus which is suitable for diagnosing whether the mechanical system of the automobile engine is working properly.
Something wrong with the engine output might be caused by an abnormality in the ignition, the gas mixture or pressure in the cylinders. The ignition and fuel can be inspected and adjusted with relative ease. However, trouble in cylinder pressure is often caused by abnormality existing in the mechanical system such as a valve, ring or piston of the engine cylinder. In addition, for inspecting and adjusting the cylinder pressure, the engine body must be removed, disassembled, and installed. Before carrying out these operations, therefore, it must be positively determined which cylinder is out of order. Erroneous determination makes labors spent for removing, disassembling and installation fruitless. When a particular cylinder among a plurality of cylinders becomes out of order, it becomes more difficult to determine the cause of the abnormality as the number of cylinders increases.
When an abnormality in the output of a particular cylinder of an engine having a multiplicity of cylinders is incurred by some cause, only an expert can locate and inspect the abnormalities, such as falling off of a gasket in the cylinder head or burning (or seizure) of a piston ring provided that the engine body must be disassembled. Even if the engine is out of order, therefore, the driver often continues to drive the car without noticing that fact. Unfortunately, leaving such an abnormality as it is often results in serious damage which results in complete breakdown of the engine.